Bag bottoming machine



1958 J. 5. DAVIS 2,847,914

4 BAG BOTTOMING MACHINE Filed March 9. 1956 4 Sheets-Sheet 1 H E ED 0 Invenhnu. Zn/w 5. flaw/'5.

J. S. DAVIS BAG BOTTOMING MACHINE Aug. 19, 1958 4 Sheets-Sheet 5 Filed March 9. 1956 John S. Dam; b w, w/fi ym y flH'ys Aug. 19, 1958 J. s. DAVIS BAG BOTTOMING MACHINE 4 Sheets-Sheet 4 Filed March 9. 1956 United States Patent C) BAG BOTTOMING MACHINE John S. Davis, Scarborough, N. Y., assignor to Equitable Paper Bag Co., Inc., Long Island, N. Y., a corporation of New York Application March 9, 1956, Serial No. 570,481

8 Claims. (Cl. 93--14) The present invention relates generally to the manufacture of paper bags and more particularly to an improved machine for efliciently forming the bottom of a paper bag.

In machines for making what in the trade is known as shopping bags, the bag is fabricated from a fiat web of kraft paper or other suitable material. This web is then formed into a tube and perforated into sections, one end of each section being folded and closed so as to constitute a so-called satchel bottom. In making a bag closure of this type, a bag tube section is usually provide with a pair of parallel slits extending inwardly from the bottom edge of the section. The end plies or opposing faces of the tube section to be closed are then separated and folded into a diamond to form the closure. The same bottoming technique is also used in the making of sacks and other types of bags in which each face is constituted by one or more plies.

One problem involved in forming the closure stems from the fact that the two plies or opposing faces of the tube section are superimposed when flat and they cannot readily be separately gripped for opening. To facilitate the opening up of the end plies, it has heretofore been the practice to cut out a notch in the paper web which, when the web is tubed, occupies a position extending inwardly from the end of the section. This notch makes it possible to grip one ply of the tube section with a mechanical finger or clip which clears the other ply through the notch therein, the other ply being held by pins whereby the finger and pins act to spread open the tube.

This expedient has several drawbacks. In cutting out the notches in the tube, small squares of kraft waste paper are formed which fall to the fioor or are scattered in the vicinity of the machine. In a high production bag-making machine, this waste paper is created in large quantities and must be repeatedly cleared from the area of the machine to prevent interference with its operation. Moreover, the existence of a notch in the satchel bottom of the bag somewhat weakens the bag closure and represents a structural disadvantage at the very point where strength is a primary consideration.

Another prior technique to facilitate the separation of the faces of the section has been to cut slits at the top end of one section, leaving a tab extending from the bottom end of the adjacent section, which tab may be gripped by a clamp to spread the plies in forming the bottom. When the finished bag which includes the extending tab is employed in automatic filling apparatus, there is a tendency for the tab to snag in the apparatus,

thereby loosening the bottom. Another disadvantage of I Patented Aug. 19, 1958 led backs and in which no discontinuities exist in the struc ture of the bottom, the top and bottom edges being perfectly even and free of tabs and notches.

More specifically it is an object of the invention to provide a bag bottoming machine in which an indented tab is formed in the end of the tube section to facilitate the opening thereof, said tab forming a temporary notch and later being pasted into the closure to fill in said notch whereby the strength of the closure is unimpaired. In a bag in accordance with the invention, no waste is created and the machine is capable of operating at high speed.

Briefly stated, in a bag making machine in accordance with the invention, the flat web is perforated to form separable sections, a tab being cut inwardly from the bottom edge of the section and being pushed down to form a temporary notch. The flat web is then shaped into a flattened tube having two single plies or two opposing faces each composed of several plies. The fiattened tubular section is then separated from the web at the perforation line and parallel slits are cut into both plies or faces of the section on either side of the tab. Thereafter the plies or faces are spread apart and folded to form a diamond having flaps defined by said slits. Finally, the flaps are folded over in superposed relation to complete the satchel bottom. In spreading apart the plies, a clamp which clears the temporary notch formed by the pushed-down tab in one ply is adapted to grip the other ply, the tab being restored to its initial position when said flaps are folded over to eliminate all discontinuities to the bottom structure.

For a better understanding of the invention, as well as other objects and further features thereof, reference is had to the following detailed description to be read in conjunction with the accompanying drawing wherein:

Fig. 1 is a schematic view showing successive stages A to E of operation in a bag machine in accordance with the invention.

Fig. 2 is a continuation of Fig. l and shows the remaining stages F to H of the machine including the final bottoming stage.

Fig. 3 is a plan view of the fiat paper web as it enters the tubing stage of the machine.

Fig. 4 is a plan view of a separated tubular bag section prior to the formation of the bottom closure.

Fig. 5 is a plan view of the bag section in the first step of forming the bottom closure.

Fig. 6 is a plan view showing the next step of forming the bottom closure.

Fig. 7 is a plan view showing the final step of forming the bottom closure.

Fig. 8 is a perspective view of the dies for slitting the tab in the tube section.

Fig. 9 is a perspective view of the bending element for pushing down the tab to form a temporary notch.

Fig. 10 is a perspective view of the delivery drum and the clamp thereon for opening the bottom of the bag section.

Fig. 11 is a perspective view of the delivery drum and rollers cooperating therewith for folding the flaps of the bottom closure.

Fig. 12 is a side view of a tubular bag section entering the bottoming drums.

Fig. 13 is a side view showing the tubular bag section after it leaves the bottoming drum to ride about the delivery drum.

Fig. 14 is a side view showing the delivery drum as it acts in conjunction with a chain driven roller for closing one flap of the bottom.

Fig. 15 is a side view showing the delivery drum as it acts in conjunction with another roller-to close the other flap of the bottom.

Referring now to the drawing, and more particularly to Fig. 1, at the input end of the paper making machine, a flat web ,10 of kraft paper drawn from a roll or any other material to be formed into bags, is fed at a first stage A into a perforator constituted by an upper cylinder 11 having a perforator bar 12 secured thereto, the upper cylinder cooperating withan idler 13 formed by a rubber covered roller. Perforation lines 14 are impressed transversely on the web at equidistant positions thereon. The spacing between successive perforations 14, as shown in Fig. ,3 determines the length of the web section 15 to be formed into a tube, .and this spacing depends on the diameter of cylinder 11. Cylinders ofdifierent diameter may be provided for tube sections of different length. Conventional drive means may he used to impart travel to the web 10.

From perforator stage A, the fiat web :10 isfed to a tab slitter, at stageB, constituted ,by a periodically actuated holder 16 supporting a pair of parallel blades 17 and cooperating with an anvil roller 18 which may be made of steel. The periodic reciprocation of the tab slitter is controlled relative to the continuously moving web so as to form two spaced slits extending inwardly from the perforation line at the lower edge of the section 15, the slits defining a square tab 19.

From tab slitter, in stage B,.the flat web feeds into a handle patch applicator in stage C in which a strip of patch material 20 and a cord handle 21 is-suppliedto cooperating rollers 22 and 23 so as toapply two spaced handles adjacent the perforation line 14 at the top of the end bag section. The handle applicator, per se, constitutes no part of the present inventionand is disclosed only to show how a complete shopping bag is fabricated inall of its details. Of course, in other types of bags without handles, the applicator stage may be omitted.

The flat web from applicator stage C thenenters-a tab bender stage D including-a rotary timed pusher or paddle 24 which is adapted to push down tab 19, as best -seen separately in Fig. 9, thereby forming a temporary-notch clearance at the bottom ofthe bag section. From the tab bender the flat web enters a tubing stage E of conventional design in which the Web is shaped into tubular form 25 and the edges adhesively joined, as shown in Fig. 3, the tab 19 standing up outside the tube. The tubular-web leaving the tubing in a flattened state.

The next stage F is shown in Fig. 2 and it includesa pair of feed rollers 26 and 27 which. supply the flattened tubular web 25 into cooperating pinch rollers. 28 and 29 provided with pinch bars 30 and 31, the pinch rollers running at a slightly retarded rate relative to the web movement so that thewe'b lies lax between the feed rollers and the pinch rollers at the moment of snap-off to be later described.

From the pinch rollers the flattened tubular web is fed into larger and somewhat faster snap-off cylinders 32 and 33, at a stage G, provided with coacting pinch bars 34 and 35. When the flattened tubular web 25 is gripped by the pinch bars 34 and 35, thegreater speed of cylinders 32 .and 33 with respect to rollers 28 and 29 applies a longitudinal stretching force to the web, snapping off the tubular section at the perforation line 14. The separated section thereupon enters a bag bottom slitter including dies 36, which, as shown in Fig. 4, cut parallel slits 37 extending longitudinally from the bottom edge on either side of tab,19, the slits cutting through both plies or opposing faces of the section against a roller 38.

From slitting stage G the'flattened tubular section enters the final or bottomer stage H where the bottom edge of the section 25 is inserted between a delivery drum 39 and a bottoming drum 40 cooperating therewith. As shown separately in Fig. 10, the flattened tubular section 25 is constituted by two plies 25a and 2512, the tab 19 being formed in ply 25a. Projecting from theperiphery '4' 1 of drum '39 is a clamping finger 41 which is adapted .to engage ply 25b and to clamp it against the surface of the drum, the finger clearing ply 25a through the temporary notch formed by tab 19. Ply 25a, on the other hand, as shown in Fig. 12, is impaled on bo-ttomer drum 40 by means of pins 42 projecting radially therefrom. Thus as the two drums rotate in opposing directions, the two plies are drawn apart and folded into a diamond to form the satchel bottom.

Before considering the mechanism for forming the satchel bottom, .we shallfirst consider the various folding operations necessary to complete the bottom as illustrated in Figs. 5 to 7. When the two piles 25a and 25b of section 25 are separated, as shown in Fig. 5,.a diamond is formed which includes two generally rectangular flaps X and Y whose edges are. defined by slits 37, flap X having tab 19. Paste is supplied to the open diamond by conventional paste bars along the path indicated 'by the dashed lines 43.

Then flap X is folded down about a creaseline 44, the bottom assuming the configuration shown in Fig. 6. Finally, flap Y is folded down about crease line 45, the flap Y overlapping flap X,as shown in Fig. 7. His important to note that in folding down flap X, the tab 19 is restoredto'its original position and there is no discontinuity or notch in the surface of the'bottom.

As shown in Fig. 12, when the plies 25a and 25b are spread apart by drums '39 and 40, the sides of the tubular section are folded in along the slit lines 37 to form the diamond. The operation of clamp finger 41 is controlled by a follower 46 which rides on a stationary arcuate cam surface 47 to cause-the clamp finger to retract, as shown in Fig. l3, whenthebag section rests on top of drum 39. Thusin the course of each rotation of drum 39,-the finger 41 is sequentially opened and closed. Creasebars or tucker blades 48 are provided to introduce the required crease lines 44 and Y45 in the diamond about which the flaps'fold.

To fold over flaps X, a roller 49- i provided which is supported between two continuous chains 50 and'51, the chains being driven by wheels-52 and-53 at a speed about twice that of the delivery drum 39 whereby roller41, which runsover the tube section 25 in the same direction as drum 39 but twice as fast, acts to press down fold .X againstthe surface of the drum. .It is. to be understood that the invention is not limited to a 2:1 speed ratio, and other overspeed relationshipsmay be used. .Fold Y is folded overfold X bya roller .60 rotatablysupportedat a fixed position which bears against the surface of the delivery drum, as shown in Fig. 15. The completed bag finally passes through discharge roller 54 and-55.

Before the bag section on the delivery drum 39 is released by the clamping finger, a clamping bar 56 mounted on the drum cooperates with the tucker blades 48 to pinch the bag section at its crease lines and thereby maintain the bag on. the drum after the finger releases same. Clamping bar 56 is controlled by a spring-biasedlever 57 having a follower-58 operating on a stationary cam 59 to effect successive clamping and release operations ,Of the clamping bar in the course of drum rotation.

While there has been shown what is considered to be a preferred embodiment of the invention, it will be manifest that many changes and modifications maybe made therein without departing from the essential spirit of 'the invention. It'is intended, therefore, inthe annexed claims to cover allsuch changes and modifications as fall within the true .scope of the invention.

"What is claimed is:

1. In a bag making machine wherein a flat web is p erforated-at spaced transverse positions to form web sections,means.to' form a tab in said flat Websection extending inwardlyfrom the bottom edge thereof, means to push down said tab to form a temporary notch, means to shape .said flat web section into a flattened tuberhaving twoopposing faces, means to form slits in both faces .on

either side of said tab extending inwardly from said bottom edge, and means to separate said faces and to fold same to form a diamond having flaps defined by said slits, said separating means including a clamp clearing said temporary notch to grip one of said faces.

2. in a bag making machine for converting a continuous paper web into a tubular bag having a satchel bottom, the combination comprising means to perforate said fiat web at spaced transverse position to form web sections, means to form a tab in said flat web section extending inwardly from the bottom edge thereof, means to push down said tab to form a temporary notch, means to shape said flat web into a flattened tube having two plies, means to form slits in both faces on either side of said tab extending inwardly from said bottom edge, and means to separate said plies and to fold same to form a diamond having flaps defined by said slits, said separating means including a clamp clearing said temporary notch to grip one of said plies, and means to fold over said flaps to complete the bottom.

3. In a bag making machine for converting a continuous paper web into a tubular bag having a satchel bottom, the combination comprising means to perforate said flat web at spaced transverse positions to form web sections, means to form a tab in said flat web section extending inwardly from the bottom edge thereof, means to push down said tab to form a temporary notch, means to shape said flat web into a flattened tube having two plies, means to separate said section from said web, means to form slits in both plies on either side of said tab extending inwardly from said bottom edge, means to spread apart said plies and to fold same to form a diamond having flaps defined by said slits, said separating means including a clamp clearing said notch to grip one of said plies, and means to fold over said flaps to complete the bottom, said last-named means restoring said flap to its initial position.

4-. In a bag making machine, means to impart travel to a bag-forming flat web, a perforator to form spaced transverse perforations in said flat web to form bag sections therein, a tab slitter to cut a tab inwardly from the bottom edge of said section, a tab bender to push down said tab to form a temporary notch, a tubing device to form said flat web into a flattened tube having opposing plies, a bag bottom slitter to form parallel slits in both plies of said tube on either side of said tab, and means to spread apart said plies including a first rotary drum having a finger thereon clearing said notch and gripping one of said plies, and a second rotary drum operating in the reverse direction and having pins to impale the other ply, said plies being folded to form a diamond having flaps defined by said slits.

5. In a shopping bag making machine, means to impart travel to a bag-forming flat web, a perforator to form spaced transverse perforations in said flat web to form bag sections, a tab slitter to cut a tab inwardly from the bottom edge of said section, a tab bender to push down said tab to form a temporary notch, a tubing device to form said flat web into a flattened tube, snapoff cylinders to separate said tube from said web, a bag bottom slitter to form parallel slits in both plies of said tube on either side of said tab, means to spread apart said plies including a delivery drum having a finger clearing said notch and gripping one of said plies, and a bottoming drum having pins to impale the other ply, said drums rotating in opposing directions, said plies being folded to form a diamond having flaps defined by said slits.

6. A shopping bag making machine comprising means to impart travel to a bag-forming fiat web, a perforator to form spaced transverse perforations in said fiat web to form sections, a tab slitter to cut a tab inwardly from the bottom edge of said section, a tab bender to push down said tab to form a temporary notch, a tubing device to form said flat web into a flattened tube, snap-off cylinders to separate said tube from said web, a bag bottom slitter to form parallel slits in both plies of said tube on either side of said tab, means to spread apart said plies including a delivery drum having a finger clearing said notch and gripping one of said plies, a bottoming drum having pins to impale the other ply, said drum rotating in opposing directions, said plies being folded to form a diamond having flaps defined by said slits, and means to fold over said flaps, said last-named means restoring said tab to its original position.

7. A bag making machine for forming bags having satchel bottoms comprising means to impart travel to a bag-forming flat web, a perforator to form spaced transverse perforations in said flat web to form sections, a tab slitter to cut a tab inwardly from the bottom edge of said section, a tab bender to push down said tab to form a temporary notch, 21 tubing device to form said flat web into a flattened tube, snap-off cylinders to sep arate said tube from said web, a bag bottom slitter to form parallel slits in both plies of said tube on either side of said tab, means to spread apart said plies including a delivery drum having a finger clearing said notch and gripping one of said plies, and a bottoming drum having pins to impale the other ply, said plies being folded to form a diamond having flaps defined by said slits, and means to fold over said flaps including a first roller travelling peripherally along said delivery drum in the direction of rotation thereof but at a relatively high speed, and a second roller rotatably mounted at a stationary position and bearing against said delivery drum, said first roller folding down one flap, said second roller folding down the other flap to overlap the first flap, said first roller restoring said tab to its initial position.

8. A machine, as set forth in claim 7, wherein said first roller is supported between a pair of continuous chains moving at an overspeed relative to said delivery drum.

References Cited in the file of this patent UNITED STATES PATENTS 519,916 Lorenz et a1. May 15, 1894 918,815 Bartholomew Apr. 20, 1909 1,583,392 Coty May 4, 1926 2,586,514 Canno Feb. 19, 1952 

